The Japanese wire service, Jiji Press reports that with the addition of eight more confirmed cases, it brings the total to 104. Nearly all of cases had visited the apparent epicenter of the outbreak, Yoyogi Park in central Tokyo.

Dengue fever is an infectious disease carried by mosquitoes and caused by any of four related dengue viruses. This disease was once called called “break-bone fever” because it sometimes causes severe joint and muscle pain that feels like bones are breaking.

Dengue fever of multiple types is found in most countries of the tropics and subtropics particularly during and after rainy season.

There are four types of dengue virus: DEN-1, DEN-2, DEN-3 and DEN-4.

People get the dengue virus from the bite of an infected Aedes mosquito. It is not contagious from person to person.